Attack helicopters are generally fitted with a medium caliber cannon placed in a nose turret. The munitions used are fitted with an impact fuze initiating the explosive charge of the shell in contact with the target or the ground. On impact with the ground the shell inevitably buries itself before being detonated, even if the delay is small. This configuration leads to considerable loss of effectiveness, all the more so when the explosive charge is relatively small.
A solution for increasing the effectiveness is to trigger detonation before impact, in proximity to the target or the ground, by fitting the explosive projectile with a proximity fuze.
Having regard to the particular configuration of firing from a helicopter, at low altitude, this proximity fuze must be compatible with very grazing firing trajectories. Moreover, the munition must be totally autonomous, without requiring any interaction with the weapons system.
The need for a munition that operates totally independently of a weapons system prohibits certain technical solutions such as those based on a chronometric function, for example a programmable-time function termed “airburst”. This type of chronometric solution requires that the munition be programmed. Moreover, the chronometric principle exhibits a major drawback. This drawback is limited precision, which is incompatible with the effectiveness of medium caliber munitions for which the precision sought is of the order of a few tens of centimeters for a nominal detection distance of between 0.5 meter and 2 meters in particular.
There is therefore a need to produce a proximity detection device, or proximity fuze:                That can be integrated into a 30-mm caliber ogive fuze, in particular;        That is totally autonomous, requiring no integration into a weapons system;        That operates in the configurations of firing from a helicopter, at grazing trajectory.        
The need can be extended to other calibers and for firing from carriers other than helicopters, ground vehicles for example.